<template>
  <div class="example">
    <div id="list-demo" class="demo">
      <transition-group name="list" tag="p">
        <span v-for="item in items" v-bind:key="item" class="list-item">
          {{ item }}
        </span>
      </transition-group>
      <div class="btn">
        <button v-on:click="add">Add</button>
        <button v-on:click="remove">Remove</button>
      </div>
    </div>
  </div>
</template>

<script>
/**
 * 例子 - 列表过渡 - 进入/离开
 */

export default {
  data() {
    return {
      items: [1,2,3,4,5,6,7,8,9],
      nextNum: 10
    }
  },
  methods: {
    randomIndex: function () {
      return Math.floor(Math.random() * this.items.length)
    },
    add: function () {
      this.items.splice(this.randomIndex(), 0, this.nextNum++)
    },
    remove: function () {
      this.items.splice(this.randomIndex(), 1)
    }
  }
}
</script>

<style lang="less" scoped>
.example {
  width: 400px;
}

.btn {
  button {
    margin-right: 10px;
  }
}

.list-item {
  display: inline-block;
  margin-right: 10px;
}
.list-enter-active, .list-leave-active {
  transition: all 1s;
}
.list-enter, .list-leave-to
/* .list-leave-active for below version 2.1.8 */ {
  opacity: 0;
  transform: translateY(30px);
}
</style>
